A newly developed Mercedes assistance system warns the driver if the car leaves its lane unintentionally. The camera on the inside of the windscreen monitors the road markings and detects when the car leaves its lane. Lane Keeping Assist will be available for the new E-Class and the S-Class from spring 2009.

Lane departure is the cause of one in six serious accidents on German roads. And more than a third of all road users killed here are involved in this type of accident. This is why Mercedes-Benz has developed this new technology – another "forward-looking" assistance system for even safer motoring. This is made possible by a camera on the inside of the windscreen, which can detect road markings by evaluating the difference in contrast between the road surface and the markings.

The image-processing system sends data to an electronic control unit, which determines the position of the car and detects when it leaves its lane on the left or right. Unlike conventional systems of this type, the Mercedes assistance system also assesses the driver's actions and, by doing so, reliably ascertains whether the car has left its lane intentionally or unintentionally. There is therefore no warning if, for example, the driver accelerates before overtaking or joining a motorway, brakes heavily or steers into a bend.

If the system determines that the car is leaving its lane unintentionally, it activates an electric motor, causing the steering wheel to vibrate – a discreet yet highly effective way of prompting the driver to countersteer. The timing of the warning depends on the width of the road and the type of lane markings. If the car crosses over a continuous line on the road, as opposed to a broken one, the system emits its warning earlier.

Lane Keeping Assist operates at speeds of between 60 and 250 km/h as soon as the system has detected a lane marking. The steering wheel does not vibrate to warn the driver if the driver ...